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The glossary provided here is largely based on “Seashells of Southern Florida: Bivalves,” by Paula M. Mikkelsen & Rüdiger Bieler, Princeton University Press. Production of this glossary was funded in part by the National Science Foundation’s Partnerships in Enhancing Expertise in Taxonomy [PEET] Program, NSF-DEB-9978119, “Bivalves - Research, Training, Electronic Dissemination of Data” (1999-2008) to Bieler and Mikkelsen.
- OCELLUS (pl. OCELLI)
- See EYE.
Type of dorsal LIGAMENT that occurs entirely on the posterior side of the UMBONES; see also AMPHIDETIC, PROSODETIC (figure: Periglypta listeri).
With the UMBONES curling posteriorly; see also PROSOGYRATE, ORTHOGYRATE.
- Expanded heel on the FOOT of some bivalves (figure: Noetia ponderosa).
- ORBITAL MUSCLES
- Marginal adductor muscles spanning the fused ventral MANTLE folds, acting as accessory adductors; occurring in such families as Periplomatidae, Hiatellidae, and Trapezidae.
- ORGAN OF DESHAYES
- Collective term for the body of nitrogen-fixing, CELLULASE-producing bacteria in the gills of Teredinidae; ducts in the afferent branchial vessels empty into the esophagus; also called Gland of Deshayes.
- ORGANS OF WILL
- Pigmented glandular structures of unknown function on the middle and inner MANTLE folds of Pinnidae; they have been shown not to be eyespots, and are possibly associated with production of pigment rays on the shell.
- See SCULPTURE.
Having the UMBONES curling directly toward one another or ventralward; see also PROSOGYRATE, OPISTHOGYRATE (figure: Tucetona pectinata).
- See LITHODESMA.
- OSCULUM (PL. OSCULA)
- See SEPTIBRANCH.
- OSSICLE, CALCAREOUS
- See LITHODESMA.
- OSTIUM (pl. OSTIA)
- An opening in (1) the ctenidia, created by the intersection of filaments and interfilamental junctions, or (2) the septum, containing gill filaments; see also EULAMELLIBRANCH, SEPTIBRANCH.
- See STATOCYST.